The present invention relates to high-speed, large-volume, automatic and continuous analysis of both the color(s) and shape (geometric form) of discrete solid particular objects such as pharmaceutical capsules. More particularly, the invention relates to the inspection and processing of large numbers of such objects, to identify the existence of and isolate (reject) virtually all "bad" or unacceptable material and to simultaneously provide an accurate running (and ultimately a total) count of the "acceptable" material.
The invention is particularly suited for use in connection with objects which intentionally are multicolored, for example, in a coded or otherwise well defined manner. Although this invention is described by way of example in connection with pharmaceutical capsules, it is to be clearly understood that the principals of this invention as well as the invention itself are applicable to and may be employed in connection with countless different types and kinds of solid discrete particular objects, including solid or multi-colored (including color-coded) objects, such as tablets or color-striped capsules.
In high-speed, large-volume processing, automated monitoring systems have become indispensable in examining the production flow to detect irregularities. Often such systems are intended primarily to replace or supplement present visual inspection methods, and thus they should be capable of achieving at least the same level, and preferably a greater level, of efficiency than that experienced with human inspectors.
Great care has been taken in for example the pharmaceutical industry to clearly delineate between different products for obvious reasons of safety. This is accomplished with various shapes and colors of the dosage forms and containers. Of these characteristics, perhaps the color most readily permits discrimination by the untrained observor having normal perception. Fortunately, the use of color to distinguish dose forms also permits rather accurate automatic machine recognition of a particular dose form. While an arrangement or system for automatic recognition by shape and/or color conceivably can take several different forms, it should be compatible with automatic process control equipment.
With particular reference to medicinal capsules, this widely recognized type of pharmaceutical dosage form is, of course, made in very large quantities. Capsules consist of a cap and body which are telescopically fitted together. Empty capsules are normally supplied assembled to automated filling machines where caps and bodies are disengaged, the bodies filled with medicinal material, and the capsules reassembled. The filled capsules are then subsequently packaged for distribution.
It is, as indicated, of utmost importance that the medicinal material in a capsule can be identified as to type and quantity by external viewing of the capsule. For this purpose, a particular capsule color combination (usually a cap of one color and body of another color) is assigned to each product item manufactured, Also, either prior to or after filling, an identification is printed on the capsules, usually in yet another (third) color.
To preclude improperly identified capsules or improperly filled capsules from entering packages and the like, meticulous inspections are performed on both empty capsules, where the elimination of capsules with imperfections also avoids impairment of the filling machines, and filled capsules.
In most capsule manufacturing installations and, until now, in all capsule filling installations, the aforementioned inspections have been performed visually by human beings. Observors view capsules being conveyed past them by some form of conveying belt, and they manually remove defective or incorrectly colored (e.g. foreign or "double-capped") capsules. The weaknesses in visual inspection are well recognized. Particularly in cases where a relatively large percentage of capsules must be removed, the inspection rate is limited by the operator's removal rate. The observer, moreover, can suffer from fatigue and/or boredom. The inspection effectiveness can reasonably be assumed to be sporadic, since it is dependent upon the inspector's physical and mental state. This visual inspection technique is very costly and sometimes fails to achieve the desired effectiveness. For instance, studies performed in filled capsule production environments indicate that about 1/2 or 2/3 of the approximately 0.6% defective capsules are discovered and removed. As to detecting foreign capsules, it is safe to say that the detection probability increases with the apparent color difference(s) between the foreign capsule(s) and the good capsules surrounding same.
It should also be recognized that capsules constitute particularly perplexing objects on which to perform color recognition and defect detection inspections. This is so because capsules are relatively small objects, which because of the great demands therefor must be inspected in large numbers and therefore at high speeds. Capsules, moreover, have highly curved surfaces leaving only very small "stable" portions of the surface thereof from which to obtain legitimate readings (particularly for color recognition). To further complicate matters, capsules have printing thereon which to such a system as this constitutes noise and could lead to the condition of too many "false positive" rejects, simply because the printing may cover as much as one-third of the entire "good" viewing area to the capsule's surface.
In U.S. Pat. No. 3,757,943, issued Sept. 11, 1973, to Chae et al, there is disclosed an invention for the inspection of empty capsules for defects. The invention disclosed in the above-cited patent detects defects by determining unplanned assymmetries in capsules. It does not, for example, have the capability of distinguishing foreign capsules, detecting symmetrical defects, or inspecting filled or printed capsules.
In U.S. Pat. No. 3,737,239, issued June 5, 1973 to Adams and Grimmell, assigned to the Assignee of the present invention, the pertinent subject matter of which is incorporated herein by reference, there is disclosed an invention for inspecting objects including pharmaceutical dose forms to determine whether their color corresponds to a standard. This invention does not particularly deal with detecting defects or inspecting multi-colored objects.
It is desirable to go beyond the disclosed art, and indeed the capsule-related prior art in general, to provide an arrangement capable inter alia of inspecting at a high rate of speed both filled and unfilled (empty) pharmaceutical capsules, both those with and without printing. Furthermore, such an arrangement should be able to inspect multi-colored capsules, particularly those with a single colored cap and possibly a different colored body, for improper color(s) and both symmetrical and non-symmetrical defects.
To be worthwhile, an automatic machine effort should provide a performance capability such that the probability of detection of (1) a foreign (wrong color[s]) capsule should be nearly unity, even where printing is present on the capsule, and (2) any structural defect should be at least 0.7 (which is greater, for example, than the capability of inspectors in a filled capsule inspection line). Moreover, the arrangement should be capable of being easily "set" to accept any specific combination or arrangement of colors, and particularly it should be capable of inspecting the two spherical ends of each capsule for correct curvature. Also, it should be capable of inspecting each capsule near its center region for indications of a chipped or split cap.